Track 17 · Lesson 4 of 12

Project: personal expense tracker

Build an expense tracker that loads and saves expenses as JSON, validates new entries, totals spending by category and month, and warns when a budget is close to running out.

You will be able to

• Design a small program as a set of single-purpose functions around one data format
• Load and save program state as JSON, handling missing, empty and corrupt files deliberately
• Validate user-supplied data and raise ValueError with a message that says what was wrong
• Aggregate records by category and by month with dictionaries
• Compare spending against budgets and produce a readable monthly report